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Extraction behavior of fission products with Tri-n-butyl phosphate by countercurrent multistage extraction in a uranium, plutonium, and neptunium Co-recovery system / Masaumi Nakahara in Industrial & engineering chemistry research, Vol. 51 N° 40 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 40 (Octobre 2012) . - pp. 13245–13250 Titre : Extraction behavior of fission products with Tri-n-butyl phosphate by countercurrent multistage extraction in a uranium, plutonium, and neptunium Co-recovery system Type de document : texte imprimé Auteurs : Masaumi Nakahara, Auteur ; Yasuo Nakajima, Auteur ; Tsutomu Koizumi, Auteur Année de publication : 2012 Article en page(s) : pp. 13245–13250 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Solvent  extraction  process Résumé : In an attempt to develop a simplified solvent extraction process for U, Pu, and Np co-recovery, three countercurrent experiments were carried out to evaluate the effect of the scrubbing solution on the decontamination of fission products (FPs) using a dissolver solution derived from the irradiated core fuel of fast reactor “JOYO”. In all the runs, Np was co-extracted with U and Pu using tri-n-butyl phosphate (TBP) at the extraction section by using high HNO3 concentration feed solution. Of all the FPs, the decontamination behavior of Zr and Tc varied with the HNO3 concentration of the scrubbing solutions. Zirconium and Tc were not decontaminated with a single scrub flow sheet, which caused the accumulation of Zr at the co-decontamination section. The decontamination factors (DFs) of Zr and Tc were 2.62 × 101 and 1.07 × 100 with flow sheet using 9 and 1 mol/dm3 HNO3 scrubbing solutions, respectively. On the other hand, their DFs increased to >7.68 × 101 and >7.52 × 100 with 2 and 10 mol/dm3 HNO3 scrubbing solutions, respectively. The experimental results indicate that it is necessary to first remove Zr from the loaded solvent with a low HNO3 concentration scrubbing solution and then decontaminate Tc using a high HNO3 concentration solution. Other FPs, such as Cs, were effectively decontaminated with DFs in the range of 105. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3011287 [article] Extraction behavior of fission products with Tri-n-butyl phosphate by countercurrent multistage extraction in a uranium, plutonium, and neptunium Co-recovery system [texte imprimé] / Masaumi Nakahara, Auteur ; Yasuo Nakajima, Auteur ; Tsutomu Koizumi, Auteur . - 2012 . - pp. 13245–13250. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 40 (Octobre 2012) . - pp. 13245–13250 Mots-clés : Solvent  extraction  process Résumé : In an attempt to develop a simplified solvent extraction process for U, Pu, and Np co-recovery, three countercurrent experiments were carried out to evaluate the effect of the scrubbing solution on the decontamination of fission products (FPs) using a dissolver solution derived from the irradiated core fuel of fast reactor “JOYO”. In all the runs, Np was co-extracted with U and Pu using tri-n-butyl phosphate (TBP) at the extraction section by using high HNO3 concentration feed solution. Of all the FPs, the decontamination behavior of Zr and Tc varied with the HNO3 concentration of the scrubbing solutions. Zirconium and Tc were not decontaminated with a single scrub flow sheet, which caused the accumulation of Zr at the co-decontamination section. The decontamination factors (DFs) of Zr and Tc were 2.62 × 101 and 1.07 × 100 with flow sheet using 9 and 1 mol/dm3 HNO3 scrubbing solutions, respectively. On the other hand, their DFs increased to >7.68 × 101 and >7.52 × 100 with 2 and 10 mol/dm3 HNO3 scrubbing solutions, respectively. The experimental results indicate that it is necessary to first remove Zr from the loaded solvent with a low HNO3 concentration scrubbing solution and then decontaminate Tc using a high HNO3 concentration solution. Other FPs, such as Cs, were effectively decontaminated with DFs in the range of 105. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3011287

Purification rate of uranyl nitrate hexahydrate crystal for transuranium elements on isothermal sweating phenomenon / Masaumi Nakahara in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010)

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11661-11666 Titre : Purification rate of uranyl nitrate hexahydrate crystal for transuranium elements on isothermal sweating phenomenon Type de document : texte imprimé Auteurs : Masaumi Nakahara, Auteur ; Kazunori Nomura, Auteur ; Tsutomu Koizumi, Auteur Année de publication : 2011 Article en page(s) : pp. 11661-11666 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Purification Résumé : For the purpose of further increasing decontamination performance, the purification behavior of uranyl nitrate hexahydrate (UNH) crystals was studied in the static system. The approach to purification of UNH crystals recovered from the irradiated fast reactor core fuel using a dissolver solution was examined by an isothermal sweating process, which involves heating to the melting point of the crystal. Since transuranium (TRU) elements were present as liquid impurities in the UNH crystal, their decontamination factors (DFs) were improved using this process. The DFs of Cs and TRU elements for the UNH crystals had a tendency to increase with time and were kept virtually constant by 240 min. Not having been precipitated as Cs2Pu(NO3)6 during the crystallization, Pu remained in the mother liquor and was removed by the sweating process. The purification rate coefficients of UNH crystals for Cs and TRU elements were calculated using these experimental data. These values for Pu, 137Cs, 241Am, and 242Cm were evaluated to be 2.13 x 10-4, 2.73 × 10-4, 2.1 × 10-4, and 3.13 x 10-4 s-1 at 57 °C, respectively. DEWEY : 660 ISSN : 0888-5885 [article] Purification rate of uranyl nitrate hexahydrate crystal for transuranium elements on isothermal sweating phenomenon [texte imprimé] / Masaumi Nakahara, Auteur ; Kazunori Nomura, Auteur ; Tsutomu Koizumi, Auteur . - 2011 . - pp. 11661-11666. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11661-11666 Mots-clés : Purification Résumé : For the purpose of further increasing decontamination performance, the purification behavior of uranyl nitrate hexahydrate (UNH) crystals was studied in the static system. The approach to purification of UNH crystals recovered from the irradiated fast reactor core fuel using a dissolver solution was examined by an isothermal sweating process, which involves heating to the melting point of the crystal. Since transuranium (TRU) elements were present as liquid impurities in the UNH crystal, their decontamination factors (DFs) were improved using this process. The DFs of Cs and TRU elements for the UNH crystals had a tendency to increase with time and were kept virtually constant by 240 min. Not having been precipitated as Cs2Pu(NO3)6 during the crystallization, Pu remained in the mother liquor and was removed by the sweating process. The purification rate coefficients of UNH crystals for Cs and TRU elements were calculated using these experimental data. These values for Pu, 137Cs, 241Am, and 242Cm were evaluated to be 2.13 x 10-4, 2.73 × 10-4, 2.1 × 10-4, and 3.13 x 10-4 s-1 at 57 °C, respectively. DEWEY : 660 ISSN : 0888-5885

Washing of uranyl nitrate hexahydrate crystals with nitric acid aqueous solution to improve crystal quality / Masaumi Nakahara in Industrial & engineering chemistry research, Vol. 51 N° 46 (Novembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp.15170–15175 Titre : Washing of uranyl nitrate hexahydrate crystals with nitric acid aqueous solution to improve crystal quality Type de document : texte imprimé Auteurs : Masaumi Nakahara, Auteur ; Yasuo Nakajima, Auteur ; Tsutomu Koizumi, Auteur Année de publication : 2013 Article en page(s) : pp.15170–15175 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Nitrate  Crystals Résumé : To develop a uranium crystallization process for advanced aqueous reprocessing, two method experiments were investigated to evaluate the effect of crystal washing on uranyl nitrate hexahydrate (UNH). In one experiment, crystal washing was carried out using a uranyl nitrate solution with varying concentrations of HNO3 in washing solutions, and in the other, it was conducted with a dissolver solution of the irradiated fast neutron reactor core fuel. In the crystal washing experiments with the uranyl nitrate solution, the UNH crystals were immersed into a uranyl nitrate solution containing Ce, which was washed out in the mother liquor on the surface of the UNH crystals using an HNO3 solution. The experimental results showed that the decontamination factor (DF) of Ce increased with decreasing HNO3 concentration of the washing solution. However, because the UNH crystals tended to dissolve in low HNO3 concentration solutions, the yield decreased as a result of the washing operation. In the crystallization experiment using a dissolver solution derived from the irradiated fast neutron reactor core fuel, the DFs of the liquid impurities for the UNH crystals were improved with each crystal washing. However, their values approached a constant value because the inclusions within the UNH crystal were not removed by the crystal washing operation. On the other hand, solid impurities such as Cs2Pu(NO3)6 and Ba(NO3)2 remained in the UNH crystals after several crystal washing operations. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3013067 [article] Washing of uranyl nitrate hexahydrate crystals with nitric acid aqueous solution to improve crystal quality [texte imprimé] / Masaumi Nakahara, Auteur ; Yasuo Nakajima, Auteur ; Tsutomu Koizumi, Auteur . - 2013 . - pp.15170–15175. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp.15170–15175 Mots-clés : Nitrate  Crystals Résumé : To develop a uranium crystallization process for advanced aqueous reprocessing, two method experiments were investigated to evaluate the effect of crystal washing on uranyl nitrate hexahydrate (UNH). In one experiment, crystal washing was carried out using a uranyl nitrate solution with varying concentrations of HNO3 in washing solutions, and in the other, it was conducted with a dissolver solution of the irradiated fast neutron reactor core fuel. In the crystal washing experiments with the uranyl nitrate solution, the UNH crystals were immersed into a uranyl nitrate solution containing Ce, which was washed out in the mother liquor on the surface of the UNH crystals using an HNO3 solution. The experimental results showed that the decontamination factor (DF) of Ce increased with decreasing HNO3 concentration of the washing solution. However, because the UNH crystals tended to dissolve in low HNO3 concentration solutions, the yield decreased as a result of the washing operation. In the crystallization experiment using a dissolver solution derived from the irradiated fast neutron reactor core fuel, the DFs of the liquid impurities for the UNH crystals were improved with each crystal washing. However, their values approached a constant value because the inclusions within the UNH crystal were not removed by the crystal washing operation. On the other hand, solid impurities such as Cs2Pu(NO3)6 and Ba(NO3)2 remained in the UNH crystals after several crystal washing operations. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3013067